If you had one of the old style engines then you know that it is not simply an issue of replacing the ignition. The plug is different. You would also have to replace the cylinder head. The crank is different as well as the drive washer. So if you want to replace the ignition you have to replace all of those. Horizon is not out of Cylinder Heads, Cranks or Drive washers. THey are only out of ignitions. That is where I made my assumptions.